1. Field of the Invention
The present invention relates to a semiconductor device and a substrate.
2. Description of the Related Art
In general, a driver to be incorporated in a liquid crystal display takes the form of a semiconductor element mounted on the display by enclosing it on a substrate constituted by tape. In a recent display driver, a D-A converter for converting a digital signal into an analog signal occupies a large percentage of the surface area of a semiconductor element as a result of the trend toward greater numbers of grayscale levels. Further, the trend toward displays having a larger size and displays incorporating a smaller number of drivers has resulted in some situations where output terminals of a quantity in excess of 720 are required per driver. In order to satisfy such a requirement, in recent drivers, a large number of wiring regions must be provided in a semiconductor element, which results in the problem that the semiconductor element will have a particularly large surface area.
Japanese Patent Application Laid-Open No. 2006-80167 addresses the problem of the increased amount of wiring in semiconductor elements and, specifically, the problem of the need to route wiring from an electrical circuit in a semiconductor element to bumps in order to extract signals from the electrical circuit. To achieve reductions in the size and weight of a semiconductor device, the document discloses a technique for connecting semiconductor element surface bumps, which serve as outputs of an electrical circuit, provided at the middle of a semiconductor element to bumps provided at a peripheral part of the semiconductor element using a wiring pattern provided on a substrate.
This technique makes it possible to connect a circuit in a semiconductor element to a wiring pattern using connection wirings. Since the connection wirings can be substituted for wirings which have been routed on or under a surface of the element, the size and weight of the semiconductor element can be reduced.
The technique disclosed in the above document allows a reduction in the amount of wiring required for output from an electrical circuit. In the case of a driver for a display, however, close attention must be paid to variations in output AC characteristics between output terminals, and it is particularly important to supply power evenly from a power supply to output units in the semiconductor element. For this reason, a power supply wiring and a ground wiring which is wired throughout the semiconductor element must be made thick enough to achieve low impedance, and the surface area of the semiconductor device is consequently increased. Therefore, reductions in the size and weight of a semiconductor element must be achieved in consideration to the above-described problems.
A driver for a display is manufactured in accordance with the layout of pins for the display (display panel) in which the driver is mounted, and the layout of pins on the semiconductor element and the layout of pins on the display does not necessarily correspond. In such a case, significant changes must be made to the existing semiconductor element.